1. Field of the Invention
The present invention relates to an image pickup unit including an image pickup optical system and an image pickup device, and an endoscope distal end portion including the image pickup unit.
2. Description of the Related Art
Conventionally, image pickup apparatuses including a solid-state image pickup device (hereinafter simply referred to as image pickup device) such as CCD or CMOS that converts light entering a light-receiving section provided in a semiconductor substrate into electric signals to pick up an image of an object have been known.
The image pickup apparatuses are used together with image pickup optical systems in electronic endoscopes and electronic equipment such as camera-equipped mobile phones and digital cameras, as image pickup units.
Also, in recent years, for the image pickup apparatuses, wafer-level chip-size package (hereinafter referred to as WL-CSP)-type ones have been known.
In WL-CSP, a cover glass wafer is attached at wafer level to a sensor wafer in which a plurality of semiconductor chips each including an image sensor formed therein are formed, and then the wafer is separated into the individual semiconductor chips, whereby a plurality of image pickup apparatus packages are completed.
A configuration using such a WL-CSP-type image pickup apparatus in an image pickup unit is disclosed in Japanese Patent Application Laid-Open Publication No. 2005-209967.
Japanese Patent Application Laid-Open Publication No. 2005-209967 discloses a configuration in which an image pickup unit includes a WL-CSP-type image pickup apparatus with a cover glass attached to a light-receiving surface of an image pickup device via a bonding layer, and a lens holder, which is a barrel body that holds an image pickup optical system, and inside the lens holder, the image pickup apparatus is provided and held at the rear, in an optical axis direction of the image pickup optical system, of the image pickup optical system, the lens holder thus covers the image pickup device and an outer circumferential face of the cover glass and thereby shields the outer circumferential face of the cover glass from light and protects the image pickup device, and the image pickup optical system is positioned relative to the image pickup device in the optical axis direction and a width direction orthogonal to the optical axis direction.